With recent improvements in the performance of digital computers, it has become possible to simulate the behavior of a large-scale object of analysis. For an easy understanding of the behavior, it is important that the result of the simulation be presented in visible form.
FIG. 1 is a diagram showing the configuration of a prior art simulation system, which comprises a simulator 10 for computing the dynamic characteristics of an object of analysis based on prescribed parameters 1 to m, a storage medium (for example, a hard disk) 11 for storing the results of the computations performed by the simulator 10, a visualization apparatus 12 for visualizing the computation results stored on the storage medium 11, and a display panel 13 for displaying the simulation results visualized by the visualizing device 12.
However, in the prior art simulation system, as the visualization is implemented as a post-process to be carried out after the simulation, the following problems arise.
1. It is difficult to observe the results in real time, upon changing the parameters, because the simulation results output from the simulator are visualized after once storing them on the storage medium.
2. For the visualization apparatus to visualize the simulation results, the simulation results stored on the hard disk or the like must be converted to a format that matches the visualization apparatus, but if the scale of the object of analysis is large, an enormous amount of computation is required for the conversion.
For example, when the viewpoint is moved, an image corresponding to the new viewpoint must be generated anew; on the other hand, when the simulation results are output as volume data for visualization with polygons, the volume data must be converted to polygons. As a result, it has not been possible to present the simulation results as images for observation in real time.
In view of this, a so-called distributed simulation system has been proposed in order to enhance simulation and visualization processing speeds.
FIG. 2 is a diagram showing the configuration of a distributed simulation system having eight nodes; in this system, the behavior of the object of analysis is computed by distributing the processing among the nodes #1 to #8, and the results of the computations are combined.
Outputs of the nodes #1 to #8 are transmitted via a communication line (for example, Message Passing Interface) and a high-speed network switcher 21 to a server 22 for display as an image on a CRT 23.
Here, to present the result of the simulation in a visually recognizable manner, the image must be updated at a rate of about 30 frames per second (video rate), which means that, as the object of analysis becomes complex, the number of nodes, that is, the number of parallel-connected computers, must be increased.
However, since there is only one communication line between the server and the nodes, if the number of nodes is increased, collisions may occur during inter-node or node-server communications, and the overhead time required for communications may become so large that it cannot be ignored.
FIG. 3 is a graph showing the relationship between the number of parallel-connected computers and the processing time, plotting the number of parallel-connected computers along the abscissa and the processing time (in seconds) along the ordinate. As shown in FIG. 3, when the number of parallel-connected computers is increased to between 50 and 100, the processing time does decrease, but on the contrary, when the number of computers is increased beyond 100, the processing time increases. When currently available CPUs are used, the processing time that can be achieved is about 0.5 second at the shortest.
The present invention has been devised in view of the above problem, and it is an object of the invention to provide a simulation system having an image generating function that can visualize the behavior of an object of analysis in real time by simulating the behavior of the object of analysis by dividing a three-dimensional space, in which an object of analysis is constructed, into a plurality of subspaces and by visualizing the result of the simulation on a subspace-by-subspace basis and thereafter blending the resulting subspace images together by considering the occlusion relationship between them.